• Handpicking, winnowing, sieving, sedimentation, decantation and filtration are some of the methods of separating substances from their mixtures.
• Methods of separation:
(i) Separation of solid from other solids:
(a) Threshing: Process by which the grains are released from the chaff.
(b) Winnowing: The process of separation of heavier and lighter components of a mixture by wind or blowing air.
(c) Hand-picking: The process by which undesirable components are just picked up by hand.
(d) Sieving: The process by which separate solid constituents of a mixture which differ in their sizes.
(e) Magnetic separation: Process by which magnet is moved over such a mixture, the magnetic material sticks to it and is removed.
(ii) Separation of water soluble solids:
(a) Evaporation: Process by which the conversion of liquid state into gaseous
state on heating.
(b) Condensation: Process by which conversion of gaseous state into liquid state on cooling.
(iii) Separation of insoluble solids from Liquids:
(a) Sedimentation: It allows heavier matter to settle down. Example: sand, water.
(b) Decantation: The methods of separating insoluble solids from liquids.
(c) Loading: The methods by which finer particles are made to settle faster by dissolving a small quantity of alum.
(d) Filtration: The liquid that collects in the beaker is called filtrate.
(iv) Separation of Immiscible Liquids:
(a) Funnel: The method of separting mixture of oil and water.
(b) Centrifugation: The method in which mixture containing suspended particles is rotated at a high speed in a centrifuge and heavier particles settle down. It is used for separating cream from milk.
(c) Churning: The method which is used for separating lighter particles of solid suspended in a liquid. Example: butter from curd.
• Husk and stones could be separated from grains by handpicking.
• Husk is separated from heavier seeds of grain by winnowing.
• A saturated solution is one in which no more of that substance can be dissolved.
• More of a substance can be dissolved in a solution by heating it.
• Water dissolves different amount of soluble substances in it.
